i) Field of the Invention
The present invention relates to a radio communication device, and more particularly to a cordless answer phone having a voice or message recording and reproducing device, which is capable of performing radio communication between base and hand sets.
ii) Description of the Related Arts
Recently, multifunctioning and multiforming are carried out to a remarkable extent in a telephone for general home use. In particular, in a party line telephone composed of a base set and a plurality of hand sets, a cordless telephone capable of performing a conversation between the base and hand sets by radio is becoming mainstream. In such a cordless party line telephone, since the conversation between the base and hand sets is performed by the radio, in order to reduce noise, cross talk and induced noise, usually, a so-called compandor circuit is provided for preventing sound quality deterioration in the communication by compressing or expanding the amplitude of a voice signal.
Further, in addition to this function, a telephone provided with a so-called automatic answering device has been widely used. In this answer phone, by using an automatic message recording and reproducing device comprised of a sound memory, a cassette tape recorder and the like, a previously recorded answer message of a telephone subscriber can be automatically played in response to a telephone call input from an external line or a telephone message input from the external line can be automatically recorded.
FIGS. 2A and 2B show a conventional cordless answer phone. First, as shown in FIG. 2A, a base set 10 is provided with a speech network part 11 having a receiving part Rx and a transmitting part Tx so as to perform control of transmission and reception between the base set 10 and a telephone subscriber line. The base set 10 also includes a compandor 12 having a compressor (COMP) 13 and an expander (EXP) 14, a radio transmission and receiving device 18 having a transmitting part Tx and a receiving part Rx, and a message recording and reproducing device 17 having a recorder REC and a player PLAY. The receiving part Rx of the speech network part 11 is connected to the transmitting part Tx of the radio transmission and receiving device 18 via the compressor 13 of the compandor 12, and the transmitting part Tx of the speech network part 11 is connected to the receiving part Rx of the radio transmission and receiving device 18 via the expander 14 of the compandor 12. The radio transmission and receiving device 18 is linked to an antenna 19 so as to carry out the transmission and reception of a radio signal between the base set 10 and a hand set 30 via the antenna 19.
Between the speech network part 11 and the compandor 12, a pair of switches 15 and 16 are connected in parallel. In each switch 15 or 16, contact points a and b are connected to the receiving part Rx side and the transmitting part Tx side of the speech network part 11, respectively. Also, a common contact point c of the switch 15 is coupled with a REC terminal of the message recording and reproducing device 17 and a microphone 24 through an amplifier 23, and a common contact point c of the switch 16 is connected to a PLAY terminal of the message recording and reproducing device 17 and a speaker 22 through an amplifier 21.
Further, as shown in FIG. 2B, the hand set 30 includes a compandor 33 having a compressor (COMP) 41 and an expander (EXP) 34 and a radio transmission and receiving device 31 having a transmitting part Tx and a receiving part Rx for performing the transmission and reception of the radio signal between the hand set 30 and the base set 10 via an antenna 32. The receiving part Rx of the radio transmission and receiving device 31 is connected to a speaker 36 via the expander 34 of the compandor 33 and an amplifier 35, and the transmitting part Tx of the radio transmission and receiving device 31 is linked with a microphone 38 via the compressor 41 of the compandor 33 and an amplifier 39.
Next, the operation of the conventional cordless answer phone described above will now be described. In this case, a usual conversation operation is carried out in the same manner as is well-known and thus the description can be omitted for brevity.
(1) Recording of an answer message of a telephone subscriber:
By inputting an answer message of the telephone subscriber, to be output in response to the call input from the external line during his absence, to the microphone 24 of the base set 10, the answer message is input to the recorder REC of the message recording and reproducing device 17 and is recorded on a magnetic tape (not shown) therein.
Also, the answer message can be recorded from the microphone 38 of the hand set 30. In this case, the answer message input from the microphone 38 is fed to the compressor 41 of the compandor 33 through the amplifier 39, and the amplitude of the voice is compressed in the compressor 41. Then, the compressed answer message is sent out from the antenna 32 via the transmitting part Tx of the radio transmission and receiving device 31. In the base set 10, the compressed answer message is received by the receiving part Rx of the radio transmission and receiving device 18 via the antenna 19, and the received answer message is input to the expander 14 of the compandor 12. At this time, the switch 15 is turned to the contact point b side. Hence, the amplitude of the voice of the compressed answer message is expanded to restore to the original voice waveform in the expander 14, and the restored answer message is input from the compressor 41 to the recorder REC of the message recording and reproducing device 17 and is recorded on the magnetic tape therein.
(2) Playing of the recorded answer message:
When a telephone call is input from the external line, by performing a predetermined call receiving process, the receiving part Rx of the speech network part 11 connects the line in the base set 10. At this time, when an automatic answer mode is selected, the answer message recorded on the magnetic tape of the message recording and reproducing device 17 is automatically played and is output from the player PLAY of the message recording and reproducing device 17. In this case, the switch 16 is turned to the contact point b side. Hence, the played answer message is sent out on the telephone subscriber line via the transmitting part Tx of the speech network part 11.
(3) Recording of a telephone message input from an external line:
When a telephone message is sent from the external line in response to the answer message, the telephone message is received by the receiving part Rx of the speech network part 11. At this time, the switch 15 is turned to the contact point a side, and thus the received telephone message is input to the recorder REC of the message recording and reproducing device 17 and is automatically recorded on the magnetic tape therein.
(4) Replaying of the recorded telephone message:
After returning home, the telephone subscriber replays the recorded telephone message by a predetermined operation in the base set 10, and the replayed telephone message is output from the player PLAY of the message recording and reproducing device 17. The telephone message is fed to the speaker 22 via the amplifier 21 and is output from the speaker 22.
Also, the telephone message can be heard from the hand set 30. In this case, when the telephone subscriber carries out a predetermined operation from the hand set 30, the switch 16 is turned to the contact point a side, and the replayed telephone message is output from the player PLAY of the message recording and reproducing device 17 and is input to the compressor 13 of the compandor 12. The amplitude of the voice of the replayed telephone message is compressed in the compressor 13, and the compressed telephone message is sent out from the antenna 19 via the transmitting part Tx of the radio transmission and receiving device 18. In the hand set 30, the compressed telephone message is received by the receiving part Rx of the radio transmission and receiving device 31 via the antenna 32, and the received telephone message is input to the expander 34 of the compandor 33. The amplitude of the voice of the received telephone message is expanded to restore to the original voice waveform in the expander 34, and the restored telephone message is sent from the expander 34 to the speaker 36 via the amplifier 35 to output the telephone message from the speaker 36.
Further, the recorded telephone message can be replayed by the telephone subscriber on an external telephone so as to listen to the recorded telephone message. In this case, when the telephone subscriber performs a predetermined operation from the external telephone, the switch 16 is turned to the contact point b side, and the replayed telephone message is output from the player PLAY of the message recording and reproducing device 17 and is sent out on the telephone subscriber line via the transmitting part Tx of the speech network part 11. Hence, the telephone subscriber can hear the telephone message recorded during his absence from the external telephone.
As described above, in the conventional cordless answer phone, since the switches for turning over the signal paths are arranged between the speech network part and the compandor, the recording and the reproducing of the answer message and the telephone message can be performed in the form of the original sound waveform. Thus, although the compandor for improving the sound quality of the radio signals is provided in both the base set and the hand set, the compandor can not be effectively used in the recording and the reproducing, and the quality of the sound recorded or reproduced can not be improved.